The use of cathodes for making copper has been prevalent for many decades. Prior art cathodes often consist of a copper hanger bar, a copper starter sheet, and a pair of copper loops by which the sheet is hung on the bar. The end portions of the bar project beyond the width of the sheet so that they may rest, for support, on the cell sides with one making the usual electrical contact, and with the starter sheet between a pair of anode plates of unrefined copper, both being immersed in the electrolyte of a refining cell, or between a pair of insoluble anodes both immersed in the electrolyte of an electro-winning cell.
The prior art cathodes are deficient in many ways. For example, the copper starter sheets are not re-usable. In other words, they cannot be stripped of the copper deposited on them and then be put back in the cell to receive a fresh copper deposit. The present and most economical practice is to melt the starter sheet copper, along with the copper deposited on it, and, from the melt, to produce wire bars, rods, billets, and other copper stock commodities in a marketable condition. Only a fraction of the melt output can be used for making fresh starter sheet, and it has been shown that it is more economical to produce fresh starter sheets electrolytically. However, the man-hour expenditure is very high because it involves stripping of starter sheets from the mother plates, flattening of the sheets, making and attaching the loops.
Another drawback with copper starter sheets is that they are not easily made truly flat, and they frequently warp in service that may give rise to short circuiting between the cathode and the anode. Short circuiting is a serious problem because it requires having the staff spending time on patrolling the tank house to remedy short circuits.
Furthermore, the loops sometimes make just a point or line contact with the support bar. This does not impair the actual copper deposit process, but it does increase resistance, and consequently, power costs are increased.
The cathode of the present invention solves some of the above-listed problems. The cathode has a solid copper hanger bar that has a flat undersurface with end portions adapted to rest upon supports and electrical contacts. A stainless steel sheet has an upper edge that is attached to the copper hanger bar with over-sized pins so that the steel sheet extends perpendicularly from the undersurface. The stainless steel sheet may also be welded to the copper hanger bar. Plastic strips may be attached to the vertical side edges of the stainless steel sheet with plastic pins that are plastic welded thereto.